Polycarbonate resins are thermoplastic resins with excellent impact resistance, heat resistance and the like and are used extensively in electrical, electronic, ITE, mechanical, automotive, building materials and other application areas. Polycarbonate resins are highly flame retardant plastic materials that possess self extinguishing properties. However, polycarbonate resin films with even better flame retardance corresponding to UL94 VTM-1 and VTM-0 are being sought in order to meet not only the requirements for exceptional clarity but also safety concerns in applications such as electrical insulation films and the like used in the field of electrical, electronic and ITE applications.
Methods employing the addition of halogenated compounds and phosphorus type compounds as flame retarding agents have previously been used to improve the flame retardance of polycarbonate resin films. The use of flame retarding agents, particularly those among them that do not contain bromine and chlorine type compounds, is desired by the market due to environmental concerns.
A flame retardant polycarbonate resin film that uses a special silicone compound containing a branched main chain structure was proposed as a substitute for flame retarding agents comprising halogen type compounds and phosphorus type compounds. (References 1 and 2) However, the problem was that the clarity was inferior to that of flame retardant polycarbonate resin films containing a flame retarding agent comprising a halogenated compound or a phosphorus type compound previously used. In addition, a flame retardant polycarbonate resin composition (Reference 3) using an organic siloxane containing alkoxy groups, vinyl groups and phenyl groups and an alkali (alkaline earth) metal salt of a perfluoroalkane sulfonic acid in order to improve the clarity was proposed. However, although the clarity improved, the flame retarding performance was only V-0 at a thickness of 1/16 inch (1.6 mm), and the film could not meet the stringent flame retardance requirements imposed on film applications.    Reference 1: Japanese Patent Application Public Disclosure No. 2007-2075    Reference 2: Japanese Patent Application Public Disclosure No. 2006-316149    Reference 3: Japanese Patent Application Public Disclosure No. H06-306265